Opheodrys vernalisSmooth Green Snake

Geographic Range

Smooth green snakes are are only native to the Nearctic region. They are found from northeastern Canada, west to Saskatchewan, south through Illinois and Virginia. There are isolated populations in areas of the western United States as well, including Wyoming, New Mexico, Iowa, Missouri, Colorado, Texas, and northern Mexico. (Harding, 1997)

Habitat

Smooth green snakes are found in moist, grassy areas, usually in prairies, pastures, meadows, marshes, and lake eges. They can also be found in open forested areas. They are most often found on the ground or climbing in low bushes. They also bask on and hide beneath rocks, logs, and other debris. (Harding, 1997)

  • Aquatic Biomes
  • lakes and ponds

Physical Description

Smooth green snakes are the only snakes in eastern North America that are entirely bright green on their upper surfaces. This coloration camouflages them well in their grassy habitats. The head is slightly wider than the neck and is green above and white below. The belly is white to pale yellow. Occasionally smooth green snakes can be brown or tan in coloration. The scales are smooth and total body length ranges from 30 to 66 cm. Males are usually smaller than females, but have longer tails. Newly hatched smooth green snakes measure 8.3 to 16.5 cm in length and tend to be less brightly colored than adults, often olive-green or bluish-gray. Smooth green snakes are harmless snakes, they are not venomous. (Harding, 1997)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range length
    30 to 66 cm
    11.81 to 25.98 in

Reproduction

Smooth green snakes mate in the spring and late summer. Females lay from 3 to 13 cylindrical eggs in shallow burrows, in rotting vegetation, or under logs or rocks. Females may share nest sites, each depositing their eggs into a single nest. Eggs are laid from June to September and the eggs hatch in August or September. Time to hatching varies quite a bit, from 4 to 30 days. This is partly a result of their ability to retain the eggs and incubate them in their body. Keeping the eggs inside the female would be beneficial to speed development because females can bask and maintain the warmth of their eggs if they are retained in her body. Young smooth green snakes mature in their second year. (Harding, 1997)

  • Breeding interval
    Smooth green snakes breed once each year.
  • Breeding season
    Females lay eggs from June to September, the young hatch in August or September.
  • Range number of offspring
    3 to 13
  • Average gestation period
    30 days
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

Once a female lays her eggs there is no further parental care of the young, though females may retain their eggs for varying amounts of time - thus warming them to speed development and protecting them from predators and injury. (Harding, 1997)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

Lifespans in the wild of smooth green snakes are unknown. One captive individual lived for 6 years.

  • Range lifespan
    Status: captivity
    6 (high) years

Behavior

Smooth green snakes are active from April through October and are mainly solitary. In winter they hibernate with groups of other snakes, including other snake species. Hibernation sites include anthills and abandoned rodent burrows. Smooth green snakes are most active during the day, though they may be active mainly in the morning and evening in hot weather. (Harding, 1997)

Communication and Perception

As other snakes, smooth green snakes rely mainly on their sense of smell, vision, and their detection vibrations to locate prey. They mainly communicate with other snakes by chemical cues and through tactile cues. (Harding, 1997)

Food Habits

Smooth green snakes eat mainly insects. They prefer crickets, grasshoppers, and caterpillars, and will also eat beetles, spiders, centipedes, millipedes, snails, slugs, and sometimes amphibians. (Harding, 1997)

  • Animal Foods
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • mollusks

Predation

Smooth green snakes are probably eaten by birds, such as hawks and American crows, by large snakes, such as milk snakes, and by some mammals, such as raccoons and foxes. They rely on their bright green color to camouflage them under most circumstances. They are fast and agile and can escape quickly, but will bite and thrash if harassed and can smear attackers with a nasty-smelling fluid. (Harding, 1997)

Ecosystem Roles

Smooth green snakes influence the populations of their insect prey and serve as a food source for predators. (Harding, 1997)

Economic Importance for Humans: Positive

Smooth green snakes help to control populations of insect pests where they are abundant. (Harding, 1997)

  • Positive Impacts
  • controls pest population

Conservation Status

Smooth green snakes have been declining in numbers and local populations have been wiped out throughout their range. This is mainly the result of habitat destruction and pesticide use. Because their diet is mainly insects, they are particularly vulnerable to the effects of insecticides that are widely sprayed in agricultural areas. (Harding, 1997)

Other Comments

Smooth green snakes, as with most snakes, don't do well in captivity. They fail to eat and do not survive for long. (Harding, 1997)

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

diurnal
  1. active during the day, 2. lasting for one day.
forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, Michigan: University of Michigan Press.